ERβ alters the chemosensitivity of luminal breast cancer cells by regulating p53 function
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Igor Bado1, Eric Pham2, Benjamin Soibam3, Fotis Nikolos1, Jan-Åke Gustafsson1,4 and Christoforos Thomas1
1Department of Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, Texas, USA
2Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
3Department of Computer Science and Engineering Technology, University of Houston-Downtown, Huston, Texas, USA
4Center for Innovative Medicine, Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
Christoforos Thomas, email: [email protected]
Keywords: estrogen receptor β; p53; breast cancer; DNA damage response; therapy response
Received: September 27, 2017 Accepted: March 21, 2018 Published: April 27, 2018
Estrogen receptor α (ERα)-positive breast cancers tend to develop resistance to both endocrine therapy and chemotherapy. Despite recent progress in defining molecular pathways that confer endocrine resistance, the mechanisms that regulate chemotherapy response in luminal tumors remain largely elusive. Luminal tumors often express wild-type p53 that is a major determinant of the cellular DNA damage response. Similar to p53, the second ER subtype, ERβ, has been reported to inhibit breast tumorigenesis by acting alone or in collaboration with p53. However, a synergistic mechanism of action has not been described. Here, we suggest that ERβ relies on p53 to elicit its tumor repressive actions in ERα-positive breast cancer cells. Upregulation of ERβ and treatment with ERβ agonists potentiates the tumor suppressor function of p53 resulting in decreased survival. This effect requires molecular interaction between the two proteins that disrupts the inhibitory action of ERα on p53 leading to increased transcriptional activity of p53. In addition, we show that the same interaction alters the chemosensitivity of endocrine-resistant cells including their response to tamoxifen therapy. Our results suggest a collaboration of ERβ and p53 tumor suppressor activity in breast cancer cells that indicates the importance of ligand-regulated ERβ as a tool to target p53 activity and improve the clinical management of resistant disease.
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